Summary for graphite sticking to kovar Discussion
Graphite sticking to Kovar is the core problem in this thread: Mark Bramble says Kovar electrodes are placed in a graphite jig and heated to about 2000F, but intermittent carbon splotches appear on the metal. He asks how to prevent or remove the deposits and why they happen, noting that buffing the graphite off leaves an undesirable finish. No definitive fix is given in the excerpt. In a later reply, Robert Belter says the issue is increasingly important for his operation too, and that finding a solution that avoids physical polishing has been elusive. He suggests exploring a pre-treatment of the Kovar before baking, mentioning boron nitride as a possibility, and also considering a combination of organic acids for cleaning without damaging the Kovar. He adds that anodic electrocleaning might be worth investigating, but does not claim it is proven.
Q. I have an operation that requires Kovar electrodes to be placed in a graphite jig while going through a furnace at approximately 2000F. Everything is fine except for intermittent splotches of carbon sticking to the metal. Has anyone seen a way to remove or prevent this type of problem, and does anyone understand why this happens? Currently, we buff the graphite off, but it produces an undesirable surface finish.
Any help/suggestions would be appreciated.
Thanks,
Mark Bramble
– Preston, Maryland, USA
2003
Q. It’s an increasingly important issue here as well, and and trying to come up with a solution that does not require some sort of physical polishing has been elusive.
I’ve been thinking more along the lines of some sort of pre-treatment of the kovar prior to baking (boron nitride, perhaps?). I’m also looking at a combination of organic acids as a clean without damaging the kovar. I don’t know if some sort of anodic electroclean would work, but it may be worth looking into as well.
Believe me when I say I know how you feel!
Robert Belter
– San Diego, California, USA
August 26, 2013